mpd/doc/user.xml

<?xml version='1.0' encoding="utf-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
                      "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">

<book>
  <title>The Music Player Daemon - User's Manual</title>

  <chapter id="intro">
    <title>Introduction</title>

    <para>
      <application>Music Player Daemon</application>
      (<application>MPD</application>) is a flexible, powerful,
      server-side application for playing music.  Through plugins and
      libraries it can play a variety of sound files while being
      controlled by its network protocol.
    </para>

    <para>
      This document is work in progress.  Most of it may be incomplete
      yet.  Please help!
    </para>
  </chapter>

  <chapter id="install">
    <title>Installation</title>

    <para>
      We recommend that you use the software installation routines of
      your distribution to install <application>MPD</application>.
      Most operating systems have a <application>MPD</application>
      package, which is very easy to install.
    </para>

    <section id="install_debian">
      <title>Installing on Debian/Ubuntu</title>

      <para>
        Install the package <application>MPD</application> via APT:
      </para>

      <programlisting>apt-get install mpd</programlisting>

      <para>
        When installed this way, <application>MPD</application> by
        default looks for music in
        <filename>/var/lib/mpd/music/</filename>; this may not be
        correct. Look at your <filename>/etc/mpd.conf</filename>
        file...
      </para>
    </section>

    <section id="install_android">
      <title>Installing on Android</title>

      <para>
        An experimental Android build is available on <ulink
        url="https://play.google.com/store/apps/details?id=org.musicpd">Google
        Play</ulink>.  After installing and launching it, MPD will
        scan the music in your <filename>Music</filename> directory
        and you can control it as usual with a MPD client.
      </para>

      <para>
        If you need to tweak the configuration, you can create a file
        called <filename>mpd.conf</filename> on the data partition
        (the directory which is returned by Android's <ulink
        url="https://developer.android.com/reference/android/os/Environment.html#getExternalStorageDirectory()">getExternalStorageDirectory()</ulink>
        API function).
      </para>
    </section>

    <section id="install_source">
      <title>Compiling from source</title>

      <para>
        Download the source tarball from <ulink
        url="http://www.musicpd.org/download.html">the
        <application>MPD</application> home page</ulink> and unpack
        it:
      </para>

      <programlisting>tar xf mpd-version.tar.xz
cd mpd-version</programlisting>

      <para>
        In any case, you need:
      </para>

      <itemizedlist>
        <listitem>
          <para>
            a C++14 compiler (e.g. <ulink
            url="http://gcc.gnu.org/">gcc 5.0</ulink> or <ulink
            url="http://clang.llvm.org/">clang 3.9</ulink>)
          </para>
        </listitem>

        <listitem>
          <para>
            <ulink url="http://www.boost.org/">Boost 1.54</ulink>
          </para>
        </listitem>

        <listitem>
          <para>
            <ulink url="https://www.freedesktop.org/wiki/Software/pkg-config/">pkg-config</ulink>
          </para>
        </listitem>
      </itemizedlist>

      <para>
        Each plugin usually needs a codec library, which you also need
        to install.  Check the plugin reference for details about
        required libraries.
      </para>

      <para>
        For example, the following installs a fairly complete list of
        build dependencies on Debian Jessie:
      </para>

      <programlisting>
apt-get install g++ \
  libmad0-dev libmpg123-dev libid3tag0-dev \
  libflac-dev libvorbis-dev libopus-dev \
  libadplug-dev libaudiofile-dev libsndfile1-dev libfaad-dev \
  libfluidsynth-dev libgme-dev libmikmod2-dev libmodplug-dev \
  libmpcdec-dev libwavpack-dev libwildmidi-dev \
  libsidplay2-dev libsidutils-dev libresid-builder-dev \
  libavcodec-dev libavformat-dev \
  libmp3lame-dev libtwolame-dev libshine-dev \
  libsamplerate0-dev libsoxr-dev \
  libbz2-dev libcdio-paranoia-dev libiso9660-dev libmms-dev \
  libzzip-dev \
  libcurl4-gnutls-dev libyajl-dev libexpat-dev \
  libasound2-dev libao-dev libjack-jackd2-dev libopenal-dev \
  libpulse-dev libroar-dev libshout3-dev \
  libsndio-dev \
  libmpdclient-dev \
  libnfs-dev libsmbclient-dev \
  libupnp-dev \
  libavahi-client-dev \
  libsqlite3-dev \
  libsystemd-dev libwrap0-dev \
  libcppunit-dev xmlto \
  libboost-dev \
  libicu-dev
      </programlisting>

      <para>
        Now configure the source tree:
      </para>

      <programlisting>./configure</programlisting>

      <para>
        The <parameter>--help</parameter> argument shows a list of
        compile-time options.  When everything is ready and
        configured, compile:
      </para>

      <programlisting>make</programlisting>

      <para>
        And install:
      </para>

      <programlisting>make install</programlisting>

      <section id="windows_build">
        <title>Compiling for Windows</title>

        <para>
          Even though it does not "feel" like a Windows application,
          <application>MPD</application> works well under Windows.
          Its build process follows the "Linux style", and may seem
          awkward for Windows people (who are not used to compiling
          their software, anyway).
        </para>

        <para>
          Basically, there are three ways to compile
          <application>MPD</application> for Windows:
        </para>

        <orderedlist>
          <listitem>
            <para>
              Build on Windows for Windows.  All you need to do is
              described above already: configure and make.
            </para>

            <para>
              For Windows users, this is kind of unusual, because few
              Windows users have a GNU toolchain and a UNIX shell
              installed.
            </para>
          </listitem>

          <listitem>
            <para>
              Build on Linux for Windows.  This is described above
              already: configure and make.  You need the <ulink
              url="https://mingw-w64.org/"><application>mingw-w64</application>
              cross compiler</ulink>.  Pass
              <parameter>--host=i686-w64-mingw32</parameter> (32 bit)
              or <parameter>--host=x86_64-w64-mingw32</parameter> (64
              bit) to configure.
            </para>

            <para>
              This is somewhat natural for Linux users.  Many
              distributions have <application>mingw-w64</application>
              packages.  The remaining difficulty here is installing
              all the external libraries.  And
              <application>MPD</application> usually needs many,
              making this method cumbersome for the casual user.
            </para>
          </listitem>

          <listitem>
            <para>
              Build on Linux for Windows using the
              <application>MPD</application>'s library build script.
            </para>
          </listitem>
        </orderedlist>

        <para>
          This section is about the latter.
        </para>

        <para>
          Just like with the native build, unpack the
          <application>MPD</application> source tarball and change
          into the directory.  Then, instead of
          <command>./configure</command>, type:
        </para>

        <programlisting>./win32/build.py --64</programlisting>

        <para>
          This downloads various library sources, and then configures
          and builds <application>MPD</application> (for x64; to build
          a 32 bit binary, pass <parameter>--32</parameter>).  The
          resulting EXE files is linked statically, i.e. it contains
          all the libraries already, and you do not need carry DLLs
          around.  It is large, but easy to use.  If you wish to have
          a small <filename>mpd.exe</filename> with DLLs, you need to
          compile manually, without the <filename>build.py</filename>
          script.
        </para>
      </section>

      <section id="android_build">
        <title>Compiling for Android</title>

        <para>
          MPD can be compiled as an Android app.  It can be installed
          easily with <link linkend="install_android">Google
          Play</link>, but if you want to build it from source, follow
          this section.
        </para>

        <para>
          You need:
        </para>

        <itemizedlist>
          <listitem>
            <para>
              Android SDK
            </para>
          </listitem>

          <listitem>
            <para>
              <ulink
              url="https://developer.android.com/ndk/downloads/index.html">Android
              NDK</ulink>
            </para>
          </listitem>
        </itemizedlist>

        <para>
          Just like with the native build, unpack the
          <application>MPD</application> source tarball and change
          into the directory.  Then, instead of
          <command>./configure</command>, type:
        </para>

        <programlisting>./android/build.py SDK_PATH NDK_PATH ABI
make android/build/mpd-debug.apk</programlisting>

        <para>
          <varname>SDK_PATH</varname> is the absolute path where you
          installed the Android SDK; <varname>NDK_PATH</varname> is
          the Android NDK installation path; <varname>ABI</varname> is
          the Android ABI to be built, e.g. "armeabi-v7a".
        </para>

        <para>
          This downloads various library sources, and then configures
          and builds <application>MPD</application>.
        </para>
      </section>
    </section>

    <section id="systemd_socket">
      <title><filename>systemd</filename> socket activation</title>

      <para>
        Using <filename>systemd</filename>, you can launch
        <application>MPD</application> on demand when the first client
        attempts to connect.
      </para>

      <para>
        <application>MPD</application> comes with two
        <application>systemd</application> unit files: a "service"
        unit and a "socket" unit.  These will only be installed when
        <application>MPD</application> was configured with
        <parameter>--with-systemdsystemunitdir=/lib/systemd/system</parameter>.
      </para>

      <para>
        To enable socket activation, type:
      </para>

      <programlisting>systemctl enable mpd.socket
systemctl start mpd.socket</programlisting>

      <para>
        In this configuration, <application>MPD</application> will
        ignore the <varname>bind_to_address</varname> and
        <varname>port</varname> settings.
      </para>
    </section>

    <section id="systemd_user">
      <title><filename>systemd</filename> user unit</title>

      <para>
        You can launch <application>MPD</application> as a
        <filename>systemd</filename> user unit.  The service file will
        only be installed when <application>MPD</application> was
        configured with
        <parameter>--with-systemduserunitdir=/usr/lib/systemd/user</parameter>
        or
        <parameter>--with-systemduserunitdir=$HOME/.local/share/systemd/user</parameter>.
      </para>

      <para>
        Once the user unit is installed, you can start and stop
        <application>MPD</application> like any other service:
      </para>

      <programlisting>systemctl --user start mpd</programlisting>

      <para>
        To auto-start <application>MPD</application> upon login, type:
      </para>

      <programlisting>systemctl --user enable mpd</programlisting>
    </section>
  </chapter>

  <chapter id="config">
    <title>Configuration</title>

    <section id="config_file">
      <title>The Configuration File</title>

      <para>
        <application>MPD</application> reads its configuration from a
        text file.  Usually, that is
        <filename>/etc/mpd.conf</filename>, unless a different path is
        specified on the command line.  If you run
        <application>MPD</application> as a user daemon (and not as a
        system daemon), the configuration is read from
        <filename>$XDG_CONFIG_HOME/mpd/mpd.conf</filename> (usually
        <filename>~/.config/mpd/mpd.conf</filename>).  On Android,
        <filename>mpd.conf</filename> will be loaded from the
        top-level directory of the data partition.
      </para>

      <para>
        Each line in the configuration file contains a setting name
        and its value, e.g.:
      </para>

      <programlisting>connection_timeout "5"</programlisting>

      <para>
        For settings which specify a filesystem path, the tilde is
        expanded:
      </para>

      <programlisting>music_directory "~/Music"</programlisting>

      <para>
        Some of the settings are grouped in blocks with curly braces,
        e.g. per-plugin settings:
      </para>

      <programlisting>audio_output {
    type "alsa"
    name "My ALSA output"
    device "iec958:CARD=Intel,DEV=0"
    mixer_control "PCM"
}</programlisting>
    </section>

    <section id="config_music_directory">
      <title>Configuring the music directory</title>

      <para>
        When you play local files, you should organize them within a
        directory called the "music directory".  This is configured in
        <application>MPD</application> with the
        <varname>music_directory</varname> setting.
      </para>

      <para>
        By default, <application>MPD</application> follows symbolic
        links in the music directory.  This behavior can be switched
        off: <varname>follow_outside_symlinks</varname> controls
        whether <application>MPD</application> follows links pointing
        to files outside of the music directory, and
        <varname>follow_inside_symlinks</varname> lets you disable
        symlinks to files inside the music directory.
      </para>

      <para>
        Instead of using local files, you can use <link
        linkend="storage_plugins">storage plugins</link> to access
        files on a remote file server.  For example, to use music from
        the SMB/CIFS server "myfileserver" on the share called
        "Music", configure the music directory
        "<parameter>smb://myfileserver/Music</parameter>".  For a
        recipe, read the <link linkend="satellite">Satellite
        MPD</link> section.
      </para>

      <para>
        You can also <link linkend="mount">use multiple storage
        plugins to assemble a virtual music directory consisting of
        multiple storages</link>.
      </para>
    </section>

    <section id="config_database_plugins">
      <title>Configuring database plugins</title>

      <para>
        If a music directory is configured, one database plugin is
        used.  To configure this plugin, add a
        <varname>database</varname> block to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>database {
    plugin "simple"
    path "/var/lib/mpd/db"
}
      </programlisting>

      <para>
        The following table lists the <varname>database</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="database_plugins">database plugin reference</link>.
      </para>
    </section>

    <section id="config_neighbor_plugins">
      <title>Configuring neighbor plugins</title>

      <para>
        All neighbor plugins are disabled by default to avoid unwanted
        overhead.  To enable (and configure) a plugin, add a
        <varname>neighbor</varname> block to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>neighbors {
    plugin "smbclient"
}
      </programlisting>

      <para>
        The following table lists the <varname>neighbor</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="neighbor_plugins">neighbor plugin reference</link>.
      </para>
    </section>

    <section id="config_input_plugins">
      <title>Configuring input plugins</title>

      <para>
        To configure an input plugin, add a <varname>input</varname>
        block to <filename>mpd.conf</filename>:
      </para>

      <programlisting>input {
    plugin "curl"
    proxy "proxy.local"
}
      </programlisting>

      <para>
        The following table lists the <varname>input</varname> options
        valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                Allows you to disable a input plugin without
                recompiling.  By default, all plugins are enabled.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="input_plugins">input plugin reference</link>.
      </para>
    </section>

    <section id="config_decoder_plugins">
      <title>Configuring decoder plugins</title>

      <para>
        Most decoder plugins do not need any special configuration.
        To configure a decoder, add a <varname>decoder</varname> block
        to <filename>mpd.conf</filename>:
      </para>

      <programlisting>decoder {
    plugin "wildmidi"
    config_file "/etc/timidity/timidity.cfg"
}
      </programlisting>

      <para>
        The following table lists the <varname>decoder</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                Allows you to disable a decoder plugin without
                recompiling.  By default, all plugins are enabled.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="decoder_plugins">decoder plugin reference</link>.
      </para>
    </section>

    <section id="config_encoder_plugins">
      <title>Configuring encoder plugins</title>

      <para>
        Encoders are used by some of the output plugins (such as <link
        linkend="shout_output"><varname>shout</varname></link>).  The
        encoder settings are included in the
        <varname>audio_output</varname> section.  More information can
        be found in the <link linkend="encoder_plugins">encoder plugin
        reference</link>.
      </para>
    </section>

    <section id="config_audio_outputs">
      <title>Configuring audio outputs</title>

      <para>
        Audio outputs are devices which actually play the audio chunks
        produced by <application>MPD</application>.  You can configure
        any number of audio output devices, but there must be at least
        one.  If none is configured, <application>MPD</application>
        attempts to auto-detect.  Usually, this works quite well with
        ALSA, OSS and on Mac OS X.
      </para>

      <para>
        To configure an audio output manually, add one or more
        <varname>audio_output</varname> blocks to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>audio_output {
    type "alsa"
    name "my ALSA device"
    device "hw:0"
}
      </programlisting>

      <para>
        The following table lists the <varname>audio_output</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>type</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>name</varname>
              </entry>
              <entry>
                The name of the audio output.  It is visible to the
                client.  Some plugins also use it internally, e.g. as
                a name registered in the PULSE server.
              </entry>
            </row>
            <row id="ao_format">
              <entry>
                <varname>format</varname>
              </entry>
              <entry>
                <para>
                  Always open the audio output with the specified
                  audio format
                  (<replaceable>samplerate:bits:channels</replaceable>),
                  regardless of the format of the input file.  This is
                  optional for most plugins.
                </para>
                <para>
                  Any of the three attributes may be an asterisk to
                  specify that this attribute should not be enforced,
                  example: <parameter>48000:16:*</parameter>.
                  <parameter>*:*:*</parameter> is equal to not having
                  a <varname>format</varname> specification.
                </para>
                <para>
                  The following values are valid for
                  <varname>bits</varname>: <varname>8</varname>
                  (signed 8 bit integer samples),
                  <varname>16</varname>, <varname>24</varname> (signed
                  24 bit integer samples padded to 32 bit),
                  <varname>32</varname> (signed 32 bit integer
                  samples), <varname>f</varname> (32 bit floating
                  point, -1.0 to 1.0), "<varname>dsd</varname>" means
                  DSD (Direct Stream Digital).  For DSD, there are
                  special cases such as "<varname>dsd64</varname>",
                  which allows you to omit the sample rate
                  (e.g. <parameter>dsd512:2</parameter> for stereo
                  DSD512, i.e. 22.5792 MHz).
                </para>
                <para>
                  The sample rate is special for DSD:
                  <application>MPD</application> counts the number of
                  bytes, not bits.  Thus, a DSD "bit" rate of 22.5792
                  MHz (DSD512) is 2822400 from
                  <application>MPD</application>'s point of view
                  (44100*512/8).
                </para>
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                  <parameter>yes|no</parameter>
              </entry>
              <entry>
                Specifies whether this audio output is enabled when
                <application>MPD</application> is started.  By
                default, all audio outputs are enabled.  This is just
                the default setting when there is no state file; with
                a state file, the previous state is restored.
              </entry>
            </row>
            <row>
              <entry>
                <varname>tags</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                If set to <parameter>no</parameter>, then
                <application>MPD</application> will not send tags to
                this output.  This is only useful for output plugins
                that can receive tags, for example the <link
                linkend="httpd_output"><varname>httpd</varname></link>
                output plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>always_on</varname>
                  <parameter>yes|no</parameter>
              </entry>
              <entry>
                If set to <parameter>yes</parameter>, then
                <application>MPD</application> attempts to keep this
                audio output always open.  This may be useful for
                streaming servers, when you don't want to disconnect
                all listeners even when playback is accidentally
                stopped.
              </entry>
            </row>
            <row>
              <entry>
                <varname>mixer_type</varname>
                <parameter>hardware|software|null|none</parameter>
              </entry>
              <entry>
                Specifies which mixer should be used for this audio
                output: the hardware mixer (available for <link
                linkend="alsa_output">ALSA</link>, <link
                linkend="oss_output">OSS</link> and <link
                linkend="pulse_output">PulseAudio</link>), the
                software mixer, the "null" mixer
                (<parameter>null</parameter>; allows setting the
                volume, but with no effect; this can be used as a
                trick to implement an <link
                linkend="external_mixer">external mixer</link>) or no
                mixer (<parameter>none</parameter>).  By default, the
                hardware mixer is used for devices which support it,
                and none for the others.
              </entry>
            </row>
            <row>
              <entry>
                <varname>replay_gain_handler</varname>
                <parameter>software|mixer|none</parameter>
              </entry>
              <entry>
                Specifies how replay gain is applied.  The default is
                <parameter>software</parameter>, which uses an
                internal software volume control.
                <parameter>mixer</parameter> uses the configured
                (hardware) mixer control.  <parameter>none</parameter>
                disables replay gain on this audio output.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>
    </section>

    <section id="config_filters">
      <title>Configuring filters</title>

      <para>
        Filters are plugins which modify an audio stream.
      </para>

      <para>
        To configure a filter, add a <varname>filter</varname> block
        to <filename>mpd.conf</filename>:
      </para>

      <programlisting>filter {
    plugin "volume"
    name "software volume"
}
      </programlisting>

      <para>
        The following table lists the <varname>filter</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>name</varname>
              </entry>
              <entry>
                The name of the filter.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>
    </section>

    <section id="config_playlist_plugins">
      <title>Configuring playlist plugins</title>

      <para>
        Playlist plugins are used to load remote playlists (protocol
        commands <command>load</command>,
        <command>listplaylist</command> and
        <command>listplaylistinfo</command>).  This is not related to
        <application>MPD</application>'s playlist directory.
      </para>

      <para>
        To configure a playlist plugin, add a
        <varname>playlist_plugin</varname> block to
        <filename>mpd.conf</filename>:
      </para>

      <programlisting>playlist_plugin {
    name "m3u"
    enabled "true"
}
      </programlisting>

      <para>
        The following table lists the
        <varname>playlist_plugin</varname> options valid for all
        plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>name</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
            <row>
              <entry>
                <varname>enabled</varname>
                <parameter>yes|no</parameter>
              </entry>
              <entry>
                Allows you to disable a input plugin without
                recompiling.  By default, all plugins are enabled.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <para>
        More information can be found in the <link
        linkend="playlist_plugins">playlist plugin reference</link>.
      </para>
    </section>

    <section id="config_audio_format">
      <title>Audio Format Settings</title>

      <section id="config_global_audio_format">
        <title>Global Audio Format</title>

        <para>
          The setting <varname>audio_output_format</varname> forces
          <application>MPD</application> to use one audio format for
          all outputs.  Doing that is usually not a good idea.  The
          values are the same as in <link
          linkend="ao_format"><varname>format</varname> in the <link
          linkend="config_audio_outputs"><varname>audio_output</varname></link>
          section</link>.
        </para>
      </section>

      <section>
        <title>Resampler</title>

        <para>
          Sometimes, music needs to be resampled before it can be
          played; for example, CDs use a sample rate of 44,100 Hz
          while many cheap audio chips can only handle 48,000 Hz.
          Resampling reduces the quality and consumes a lot of CPU.
          There are different options, some of them optimized for high
          quality and others for low CPU usage, but you can't have
          both at the same time.  Often, the resampler is the
          component that is responsible for most of
          <application>MPD</application>'s CPU usage.  Since
          <application>MPD</application> comes with high quality
          defaults, it may appear that <application>MPD</application>
          consumes more CPU than other software.
        </para>

        <para>
          Check the <link linkend="resampler_plugins">resampler plugin
          reference</link> for a list of resamplers and how to
          configure them.
        </para>
      </section>
    </section>

    <section id="config_other">
      <title>Other Settings</title>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>Setting</entry>
              <entry>Description</entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>metadata_to_use</varname>
                <parameter>TAG1,TAG2,...</parameter>
              </entry>
              <entry>
                Use only the specified tags, and ignore the others.
                This setting can reduce the database size and
                <application>MPD</application>'s memory usage by
                omitting unused tags.  By default, all tags but
                <varname>comment</varname> are enabled.  The special
                value "none" disables all tags.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <section>
        <title>The State File</title>

        <para>
          The <emphasis>state file</emphasis> is a file where
          <application>MPD</application> saves and restores its state
          (play queue, playback position etc.) to keep it persistent
          across restarts and reboots.  It is an optional setting.
        </para>

        <para>
          <application>MPD</application> will attempt to load the
          state file during startup, and will save it when shutting
          down the daemon.  Additionally, the state file is refreshed
          every two minutes (after each state change).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>state_file</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Specify the state file location.  The parent
                  directory must be writable by the
                  <application>MPD</application> user
                  (<parameter>+wx</parameter>).
                </entry>
              </row>

              <row>
                <entry>
                  <varname>state_file_interval</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  Auto-save the state file this number of seconds
                  after each state change.  Defaults to
                  <parameter>120</parameter> (2 minutes).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="stickers">
        <title>The Sticker Database</title>

        <para>
          "Stickers" are pieces of information attached to songs.
          Some clients use them to store ratings and other volatile
          data.  This feature requires <ulink
          url="http://www.sqlite.org/">SQLite</ulink>, compile-time
          configure option <parameter>--enable-sqlite</parameter>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>sticker_file</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  The location of the sticker database.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title>Resource Limitations</title>

        <para>
          These settings are various limitations to prevent
          <application>MPD</application> from using too many
          resources (denial of service).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>

              <row>
                <entry>
                  <varname>connection_timeout</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  If a client does not send any new data in this time
                  period, the connection is closed.  Clients waiting
                  in "idle" mode are excluded from this.  Default is
                  <parameter>60</parameter>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_connections</varname>
                  <parameter>NUMBER</parameter>
                </entry>
                <entry>
                  This specifies the maximum number of clients that
                  can be connected to <application>MPD</application>
                  at the same time.  Default is
                  <parameter>5</parameter>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_playlist_length</varname>
                  <parameter>NUMBER</parameter>
                </entry>
                <entry>
                  The maximum number of songs that can be in the
                  playlist.  Default is <parameter>16384</parameter>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_command_list_size</varname>
                  <parameter>KBYTES</parameter>
                </entry>
                <entry>
                  The maximum size a command list.  Default is
                  <parameter>2048</parameter> (2 MiB).
                </entry>
              </row>

              <row>
                <entry>
                  <varname>max_output_buffer_size</varname>
                  <parameter>KBYTES</parameter>
                </entry>
                <entry>
                  The maximum size of the output buffer to a client
                  (maximum response size).  Default is
                  <parameter>8192</parameter> (8 MiB).
                </entry>
              </row>

            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title>Buffer Settings</title>

        <para>
          Do not change these unless you know what you are doing.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>

              <row>
                <entry>
                  <varname>audio_buffer_size</varname>
                  <parameter>KBYTES</parameter>
                </entry>
                <entry>
                  Adjust the size of the internal audio buffer.
                  Default is <parameter>4096</parameter> (4 MiB).
                </entry>
              </row>

              <row>
                <entry>
                  <varname>buffer_before_play</varname>
                  <parameter>PERCENT</parameter>
                </entry>
                <entry>
                  Control the percentage of the buffer which is filled
                  before beginning to play.  Increasing this reduces
                  the chance of audio file skipping, at the cost of
                  increased time prior to audio playback.  Default is
                  <parameter>10%</parameter>.
                </entry>
              </row>

            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="zeroconf">
        <title>Zeroconf</title>

        <para>
          If Zeroconf support (<ulink
          url="http://avahi.org/">Avahi</ulink> or Apple's Bonjour)
          was enabled at compile time with
          <parameter>--with-zeroconf=...</parameter>, MPD can announce
          its presence on the network.  The following settings control
          this feature:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>

              <row>
                <entry>
                  <varname>zeroconf_enabled</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Enables or disables this feature.  Default is
                  <parameter>yes</parameter>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>zeroconf_name</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  The service name to publish via Zeroconf.  The
                  default is "<parameter>Music Player</parameter>".
                </entry>
              </row>

            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>
  </chapter>

  <chapter id="advanced_config">
    <title>Advanced configuration</title>

    <section id="satellite">
      <title>Satellite setup</title>

      <para>
        <application>MPD</application> runs well on weak machines such
        as the <ulink url="http://www.raspberrypi.org/">Raspberry
        Pi</ulink>.  However, such hardware tends to not have storage
        big enough to hold a music collection.  Mounting music from a
        file server can be very slow, especially when updating the
        database.
      </para>

      <para>
        One approach for optimization is running
        <application>MPD</application> on the file server, which not
        only exports raw files, but also provides access to a readily
        scanned database.  Example configuration:
      </para>

      <programlisting>music_directory "nfs://fileserver.local/srv/mp3"
#music_directory "smb://fileserver.local/mp3"

database {
    plugin "proxy"
    host "fileserver.local"
}
      </programlisting>

      <para>
        The <link
        linkend="config_music_directory"><varname>music_directory</varname></link>
        setting tells <application>MPD</application> to read files
        from the given NFS server.  It does this by connecting to the
        server from userspace.  This does not actually mount the file
        server into the kernel's virtual file system, and thus
        requires no kernel cooperation and no special privileges.  It
        does not even require a kernel with NFS support, only the
        <link linkend="nfs_storage"><filename>nfs</filename></link>
        storage plugin (using the <filename>libnfs</filename>
        userspace library).  The same can be done with SMB/CIFS using
        the <link
        linkend="smbclient_storage"><filename>smbclient</filename></link>
        storage plugin (using <filename>libsmbclient</filename>).
      </para>

      <para>
        The <link
        linkend="config_database_plugins"><varname>database</varname></link>
        setting tells <application>MPD</application> to pass all
        database queries on to the <application>MPD</application>
        instance running on the file server (using the <link
        linkend="proxy_database"><filename>proxy</filename></link>
        plugin).
      </para>
    </section>

    <section id="realtime">
      <title>Real-Time Scheduling</title>

      <para>
        On Linux, <application>MPD</application> attempts to configure
        <ulink
        url="https://en.wikipedia.org/wiki/Real-time_computing">real-time
        scheduling</ulink> for some threads that benefit from it.
      </para>

      <para>
        This is only possible you allow <application>MPD</application>
        to do it.  This privilege is controlled by
        <varname>RLIMIT_RTPRIO</varname>
        <varname>RLIMIT_RTTIME</varname>.  You can configure this
        privilege with <command>ulimit</command> before launching
        <application>MPD</application>:
      </para>

      <programlisting>ulimit -HS -r 50; mpd</programlisting>

      <para>
        Or you can use the <command>prlimit</command> program from the
        <application>util-linux</application> package:
      </para>

      <programlisting>prlimit --rtprio=50 --rttime=unlimited mpd</programlisting>

      <para>
        The <application>systemd</application> service file shipped
        with <application>MPD</application> comes with this setting.
      </para>

      <para>
        This works only if the Linux kernel was compiled with
        <varname>CONFIG_RT_GROUP_SCHED</varname> disabled.  Use the
        following command to check this option for your current
        kernel:
      </para>

      <programlisting>zgrep ^CONFIG_RT_GROUP_SCHED /proc/config.gz</programlisting>

      <para>
        You can verify whether the real-time scheduler is active with
        the <command>ps</command> command:
      </para>

      <programlisting># ps H -q `pidof -s mpd` -o 'pid,tid,cls,rtprio,comm'
  PID   TID CLS RTPRIO COMMAND
16257 16257  TS      - mpd
16257 16258  TS      - io
16257 16259  FF     50 rtio
16257 16260  TS      - player
16257 16261  TS      - decoder
16257 16262  FF     50 output:ALSA
16257 16263 IDL      0 update</programlisting>

      <para>
        The <varname>CLS</varname> column shows the CPU scheduler;
        <parameter>TS</parameter> is the normal scheduler;
        <parameter>FF</parameter> and <parameter>RR</parameter> are
        real-time schedulers.  In this example, two threads use the
        real-time scheduler: the <command>output</command> thread and
        the <command>rtio</command> (real-time I/O) thread; these two
        are the important ones.  The database update thread uses the
        idle scheduler ("<parameter>IDL</parameter> in
        <command>ps</command>), which only gets CPU when no other
        process needs it.
      </para>

      <note>
        <para>
          There is a rumor that real-time scheduling improves audio
          quality.  That is not true.  All it does is reduce the
          probability of skipping (audio buffer xruns) when the
          computer is under heavy load.
        </para>
      </note>
    </section>
  </chapter>

  <chapter id="use">
    <title>Using <application>MPD</application></title>

    <section id="client">
      <title>The client</title>

      <para>
        After you have installed, configured and started
        <application>MPD</application>, you choose a client to control
        the playback.
      </para>

      <para>
        The most basic client is <filename>mpc</filename>, which
        provides a command line interface.  It is useful in shell
        scripts.  Many people bind specific <filename>mpc</filename>
        commands to hotkeys.
      </para>

      <para>
        The <ulink
        url="http://www.musicpd.org/clients/"><application>MPD</application>
        Wiki</ulink> contains an extensive list of clients to choose
        from.
      </para>
    </section>

    <section id="music_directory_and_database">
      <title>The music directory and the database</title>

      <para>
        The "music directory" is where you store your music files.
        <application>MPD</application> stores all relevant meta
        information about all songs in its "database".  Whenever you
        add, modify or remove songs in the music directory, you have
        to update the database, for example with
        <filename>mpc</filename>:
      </para>

      <programlisting>mpc update</programlisting>

      <para>
        Depending on the size of your music collection and the speed
        of the storage, this can take a while.
      </para>

      <para>
        To exclude a file from the update, create a file called
        <filename>.mpdignore</filename> in its parent directory.  Each
        line of that file may contain a list of shell wildcards.
        Matching files in the current directory and all subdirectories
        are excluded.
      </para>

      <section id="mount">
        <title>Mounting other storages into the music directory</title>

        <para>
          <application>MPD</application> has various <link
          linkend="storage_plugins">storage plugins</link> of which
          multiple instances can be "mounted" into the music
          directory.  This way, you can use local music, file servers
          and USB sticks at the same time.  Example:
        </para>

        <programlisting>mpc mount foo nfs://192.168.1.4/export/mp3
mpc mount usbstick udisks://by-uuid-2F2B-D136
mpc unmount usbstick</programlisting>

        <para>
          MPD's <link
          linkend="neighbor_plugins">neighbor plugins</link> can be
          helpful with finding mountable storages:
        </para>

        <programlisting>mpc listneighbors</programlisting>
      </section>
    </section>

    <section id="tags">
      <title>Metadata</title>

      <para>
        When scanning or playing a song,
        <application>MPD</application> parses its metadata.  The
        following tags are supported:
      </para>

      <xi:include href="include/tags.xml"
                  xmlns:xi="http://www.w3.org/2001/XInclude"/>
    </section>

    <section id="queue">
      <title>The queue</title>

      <para>
        The queue (sometimes called "current playlist") is a list of
        songs to be played by <application>MPD</application>.  To play
        a song, add it to the queue and start playback.  Most clients
        offer an interface to edit the queue.
      </para>
    </section>

    <section id="stored_playlists">
      <title>Stored Playlists</title>

      <para>
        Stored playlists are some kind of secondary playlists which
        can be created, saved, edited and deleted by the client.  They
        are addressed by their names.  Its contents can be loaded into
        the queue, to be played back.  The
        <varname>playlist_directory</varname> setting specifies where
        those playlists are stored.
      </para>
    </section>
  </chapter>

  <chapter id="advanced_usage">
    <title>Advanced usage</title>

    <section id="bit_perfect">
      <title>Bit-perfect playback</title>

      <para>
        "Bit-perfect playback" is a phrase used by audiophiles to
        describe a setup that plays back digital music as-is, without
        applying any modifications such as resampling, format
        conversion or software volume.  Naturally, this implies a
        lossless codec.
      </para>

      <para>
        By default, <application>MPD</application> attempts to do
        bit-perfect playback, unless you tell it not to.  Precondition
        is a sound chip that supports the audio format of your music
        files.  If the audio format is not supported,
        <application>MPD</application> attempts to fall back to the
        nearest supported audio format, trying to lose as little
        quality as possible.
      </para>

      <para>
        To verify if <application>MPD</application> converts the audio
        format, enable verbose logging, and watch for these lines:
      </para>

      <programlisting>decoder: audio_format=44100:24:2, seekable=true
output: opened plugin=alsa name="An ALSA output" audio_format=44100:16:2
output: converting from 44100:24:2</programlisting>

      <para>
        This example shows that a 24 bit file is being played, but the
        sond chip cannot play 24 bit.  It falls back to 16 bit,
        discarding 8 bit.
      </para>

      <para>
        However, this does not yet prove bit-perfect playback;
        <application>ALSA</application> may be fooling
        <application>MPD</application> that the audio format is
        supported.  To verify the format really being sent to the
        physical sound chip, try:
      </para>

      <programlisting>cat /proc/asound/card*/pcm*p/sub*/hw_params
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 44100 (44100/1)
period_size: 4096
buffer_size: 16384</programlisting>

      <para>
        Obey the "format" row, which indicates that the current
        playback format is 16 bit (signed 16 bit integer, little
        endian).
      </para>

      <para>
        Check list for bit-perfect playback:
      </para>

      <itemizedlist>
        <listitem>
          <para>
            Use the <link linkend="alsa_output">ALSA</link> output
            plugin.
          </para>
        </listitem>

        <listitem>
          <para>
            Disable sound processing inside
            <application>ALSA</application> by configuring a
            "hardware" device (<parameter>hw:0,0</parameter> or
            similar).
          </para>
        </listitem>

        <listitem>
          <para>
            Don't use software volume (setting <link
            linkend="config_audio_outputs"><varname>mixer_type</varname></link>).
          </para>
        </listitem>

        <listitem>
          <para>
            Don't force <application>MPD</application> to use a
            specific audio format (settings <link
            linkend="config_audio_outputs"><varname>format</varname></link>,
            <link
            linkend="config_global_audio_format"><varname>audio_output_format</varname></link>).
          </para>
        </listitem>

        <listitem>
          <para>
            Verify that you are really doing bit-perfect playback
            using <application>MPD</application>'s verbose log and
            <filename>/proc/asound/card*/pcm*p/sub*/hw_params</filename>.
            Some DACs can also indicate the audio format.
          </para>
        </listitem>
      </itemizedlist>
    </section>

    <section id="dsd">
      <title>Direct Stream Digital (DSD)</title>

      <para>
        DSD (<ulink
        url="https://en.wikipedia.org/wiki/Direct_Stream_Digital">Direct
        Stream Digital</ulink>) is a digital format that stores audio
        as a sequence of single-bit values at a very high sampling
        rate.
      </para>

      <para>
        <application>MPD</application> understands the file formats
        <link linkend="dsdiff_decoder"><filename>dff</filename></link>
        and <link
        linkend="dsf_decoder"><filename>dsf</filename></link>.  There
        are three ways to play back DSD:
      </para>

      <itemizedlist>
        <listitem>
          <para>
            Native DSD playback.  Requires
            <application>ALSA</application> 1.0.27.1 or later, a sound
            driver/chip that supports DSD and of course a DAC that
            supports DSD.
          </para>
        </listitem>

        <listitem>
          <para>
            DoP (DSD over PCM) playback.  This wraps DSD inside fake
            24 bit PCM according to the <ulink
            url="http://dsd-guide.com/dop-open-standard">DoP
            standard</ulink>.  Requires a DAC that supports DSD.  No
            support from ALSA and the sound chip required (except for
            <link linkend="bit_perfect">bit-perfect</link> 24 bit PCM
            support).
          </para>
        </listitem>

        <listitem>
          <para>
            Convert DSD to PCM on-the-fly.
          </para>
        </listitem>
      </itemizedlist>

      <para>
        Native DSD playback is used automatically if available.  DoP
        is only used if enabled explicitly using the <link
        linkend="alsa_output"><varname>dop</varname></link> option,
        because there is no way for <application>MPD</application> to
        find out whether the DAC supports it.  DSD to PCM conversion
        is the fallback if DSD cannot be used directly.
      </para>
    </section>
  </chapter>

  <chapter id="client_hacks">
    <title>Client Hacks</title>

    <section id="external_mixer">
      <title>External Mixer</title>

      <para>
        The setting '<varname>mixer_type</varname>
        "<parameter>null</parameter>"' asks
        <application>MPD</application> to pretend that there is a
        mixer, but not actually do something.  This allows you to
        implement a <application>MPD</application> client which
        listens for <varname>mixer</varname> events, queries the
        current (fake) volume, and uses it to program an external
        mixer.  For example, your client can forward this setting to
        your amplifier.
      </para>
    </section>
  </chapter>

  <chapter id="troubleshooting">
    <title>Troubleshooting</title>

    <section id="troubleshooting_start">
      <title>Where to start</title>

      <para>
        Make sure you have the latest <application>MPD</application>
        version (via <command>mpd --version</command>, not
        <command>mpc version</command>).  All the time, bugs are found
        and fixed, and your problem might be a bug that is fixed
        already.  Do not ask for help unless you have the latest
        <application>MPD</application> version.  The most common
        excuse is when your distribution ships an old
        <application>MPD</application> version - in that case, please
        ask your distribution for help, and not the
        <application>MPD</application> project.
      </para>

      <para>
        Check the log file.  Configure '<varname>log_level</varname>
        "<parameter>verbose</parameter>"' or pass
        <parameter>--verbose</parameter> to <filename>mpd</filename>.
      </para>

      <para>
        Sometimes, it is helpful to run <application>MPD</application>
        in a terminal and follow what happens.  This is how to do it:
      </para>

      <programlisting>mpd --stdout --no-daemon --verbose</programlisting>
    </section>

    <section id="support">
      <title>Support</title>

      <section id="help">
        <title>Getting Help</title>

        <para>
          The <application>MPD</application> project runs <ulink
          url="https://forum.musicpd.org/">a forum</ulink> and an IRC
          channel (<varname>#mpd</varname> on Freenode) for requesting
          help.  Visit <ulink url="https://www.musicpd.org/help/">the
          <application>MPD</application> help page</ulink> for details
          on how to get help.
        </para>
      </section>

      <section id="faq">
        <title>Common Problems</title>

        <qandaset defaultlabel='qanda'>
          <qandadiv>
            <title>Database</title>

            <qandaentry>
              <question>
                <para>
                  I can't see my music in the
                  <application>MPD</application> database!
                </para>
              </question>
              <answer>
                <itemizedlist>
                  <listitem>
                    <para>
                      Check your <varname>music_directory</varname>
                      setting.
                    </para>
                  </listitem>
                </itemizedlist>
                <itemizedlist>
                  <listitem>
                    <para>
                      Does the <application>MPD</application> user
                      have read permission on all music files, and
                      read+execute permission on all music directories
                      (and all of their parent directories)?
                    </para>
                  </listitem>
                </itemizedlist>
                <itemizedlist>
                  <listitem>
                    <para>
                      Did you update the database?  (<command>mpc
                      update</command>)
                    </para>
                  </listitem>
                </itemizedlist>
                <itemizedlist>
                  <listitem>
                    <para>
                      Did you enable all relevant decoder plugins at
                      compile time?  <command>mpd --version</command>
                      will tell you.
                    </para>
                  </listitem>
                </itemizedlist>
              </answer>
            </qandaentry>

            <qandaentry>
              <question>
                <para>
                  <application>MPD</application> doesn't read ID3
                  tags!
                </para>
              </question>
              <answer>
                <para>
                  You probably compiled <application>MPD</application>
                  without <filename>libid3tag</filename>.
                  <command>mpd --version</command> will tell you.
                </para>
              </answer>
            </qandaentry>
          </qandadiv>

          <qandadiv>
            <title>Playback</title>

            <qandaentry>
              <question>
                <para>I can't hear music on my client!</para>
              </question>
              <answer>
                <para>
                  That problem usually follows a misunderstanding of the
                  nature of <application>MPD</application>.
                  <application>MPD</application> is a remote-controlled
                  music player, not a music distribution system.
                  Usually, the speakers are connected to the box where
                  <application>MPD</application> runs, and the
                  <application>MPD</application> client only sends
                  control commands, but the client does not actually
                  play your music.
                </para>

                <para>
                  <application>MPD</application> has output plugins
                  which allow hearing music on a remote host (such as
                  <link
                      linkend="httpd_output"><varname>httpd</varname></link>),
                  but that is not <application>MPD</application>'s
                  primary design goal.
                </para>
              </answer>
            </qandaentry>

            <qandaentry>
              <question>
                <para>"Device or resource busy"</para>
              </question>
              <answer>
                <para>
                  This ALSA error means that another program uses your
                  sound hardware exclusively.  You can stop that
                  program to allow <application>MPD</application> to
                  use it.
                </para>
                <para>
                  Sometimes, this other program is
                  <application>PulseAudio</application>, which can
                  multiplex sound from several applications, to allow
                  them to share your sound chip.  In this case, it
                  might be a good idea for <link
                  linkend="pulse_output"><application>MPD</application>
                  to use <application>PulseAudio</application></link>
                  as well, instead of using ALSA directly.
                </para>
              </answer>
            </qandaentry>
          </qandadiv>
        </qandaset>
      </section>
    </section>

    <section id="bugs">
      <title>Reporting Bugs</title>

      <para>
        If you believe you found a bug in
        <application>MPD</application>, report it on <ulink
        url="https://github.com/MusicPlayerDaemon/MPD/issues/">the bug
        tracker</ulink>.
      </para>

      <para>
        Your bug report should contain:
      </para>

      <itemizedlist>
        <listitem>
          <para>
            the output of <command>mpd --version</command>
          </para>
        </listitem>

        <listitem>
          <para>
            your <link linkend="config_file">configuration file</link>
            (<filename>mpd.conf</filename>)
          </para>
        </listitem>

        <listitem>
          <para>
            relevant portions of the log file (--verbose)
          </para>
        </listitem>

        <listitem>
          <para>
            be clear about what you expect MPD to do, and what is
            actually happening
          </para>
        </listitem>
      </itemizedlist>

      <section id="crash">
        <title><application>MPD</application> crashes</title>

        <para>
          All <application>MPD</application> crashes are bugs which
          must be fixed by a developer, and you should write a bug
          report.  (Many crash bugs are caused by codec libraries
          used by <application>MPD</application>, and then that
          library must be fixed; but in any case, the
          <application>MPD</application> bug tracker is a good place
          to report it first if you don't know.)
        </para>

        <para>
          A crash bug report needs to contain a "backtrace".
        </para>

        <para>
          First of all, your <application>MPD</application> executable
          must not be "stripped" (i.e. debug information deleted).
          The executables shipped with Linux distributions are usually
          stripped, but some have so-called "debug" packages (package
          <filename>mpd-dbg</filename> or
          <filename>mpd-dbgsym</filename> on Debian,
          <filename>mpd-debug</filename> on other distributions).
          Make sure this package is installed.
        </para>

        <para>
          You can extract the backtrace from a core dump, or by
          running <application>MPD</application> in a debugger, e.g.:
        </para>

        <programlisting>gdb --args mpd --stdout --no-daemon --verbose
run</programlisting>

        <para>
          As soon as you have reproduced the crash, type
          "<command>bt</command>" on the <filename>gdb</filename>
          command prompt.  Copy the output to your bug report.
        </para>
      </section>
    </section>
  </chapter>

  <chapter id="plugin_reference">
    <title>Plugin reference</title>

    <section id="database_plugins">
      <title>Database plugins</title>

      <section>
        <title><varname>simple</varname></title>

        <para>
          The default plugin.  Stores a copy of the database in
          memory.  A file is used for permanent storage.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>path</varname>
                </entry>
                <entry>
                  The path of the database file.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>cache_directory</varname>
                </entry>
                <entry>
                  The path of the cache directory for additional
                  storages mounted at runtime.  This setting is
                  necessary for the <command>mount</command> protocol
                  command.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>compress</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Compress the database file using
                  <filename>gzip</filename>?  Enabled by default (if
                  built with <filename>zlib</filename>).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="proxy_database">
        <title><varname>proxy</varname></title>

        <para>
          Provides access to the database of another
          <application>MPD</application> instance using
          <filename>libmpdclient</filename>.  This is useful when you
          run mount the music directory via NFS/SMB, and the file
          server already runs a <application>MPD</application>
          instance.  Only the file server needs to update the
          database.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>host</varname>
                </entry>
                <entry>
                  The host name of the "master"
                  <application>MPD</application> instance.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>port</varname>
                </entry>
                <entry>
                  The port number of the "master"
                  <application>MPD</application> instance.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>password</varname>
                </entry>
                <entry>
                  The password used to log in to the "master"
                  <application>MPD</application> instance.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>keepalive</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Send TCP keepalive packets to the "master"
                  <application>MPD</application> instance?  This option can
                  help avoid certain firewalls dropping inactive
                  connections, at the expensive of a very small amount of
                  additional network traffic.  Disabled by default.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>upnp</varname></title>

        <para>
          Provides access to UPnP media servers.
        </para>
      </section>
    </section>

    <section id="storage_plugins">
      <title>Storage plugins</title>

      <section>
        <title><varname>local</varname></title>

        <para>
          The default plugin which gives
          <application>MPD</application> access to local files.  It is
          used when <varname>music_directory</varname> refers to a
          local directory.
        </para>
      </section>

      <section id="curl_storage">
        <title><varname>curl</varname></title>

        <para>
          A WebDAV client using <filename>libcurl</filename>.  It is
          used when <varname>music_directory</varname> contains a
          <parameter>http://</parameter> or
          <parameter>https://</parameter> URI, for example
          "<parameter>https://the.server/dav/</parameter>".
        </para>
      </section>

      <section id="smbclient_storage">
        <title><varname>smbclient</varname></title>

        <para>
          Load music files from a SMB/CIFS server.  It is used when
          <varname>music_directory</varname> contains a
          <parameter>smb://</parameter> URI, for example
          "<parameter>smb://myfileserver/Music</parameter>".
        </para>
      </section>

      <section id="nfs_storage">
        <title><varname>nfs</varname></title>

        <para>
          Load music files from a NFS server.  It is used when
          <varname>music_directory</varname> contains a
          <parameter>nfs://</parameter> URI according to <ulink
          url="http://tools.ietf.org/html/rfc2224">RFC2224</ulink>,
          for example "<parameter>nfs://servername/path</parameter>".
        </para>

        <para>
          This plugin uses <ulink
          url="https://github.com/sahlberg/libnfs"><filename>libnfs</filename></ulink>,
          which supports only NFS version 3.  Since
          <application>MPD</application> is not allowed to bind to
          "privileged ports", the NFS server needs to enable the
          "insecure" setting; example
          <filename>/etc/exports</filename>:
        </para>

        <programlisting>/srv/mp3 192.168.1.55(ro,insecure)</programlisting>

        <para>
          Don't fear: "insecure" does not mean that your NFS server is
          insecure.  A few decades ago, people thought the concept of
          "privileged ports" would make network services "secure",
          which was a fallacy.  The absence of this obsolete
          "security" measure means little.
        </para>
      </section>
    </section>

    <section id="neighbor_plugins">
      <title>Neighbor plugins</title>

      <section id="smbclient_neighbor">
        <title><varname>smbclient</varname></title>

        <para>
          Provides a list of SMB/CIFS servers on the local network.
        </para>
      </section>

      <section id="upnp_neighbor">
        <title><varname>upnp</varname></title>

        <para>
          Provides a list of UPnP servers on the local network.
        </para>
      </section>
    </section>

    <section id="input_plugins">
      <title>Input plugins</title>

      <section>
        <title><varname>alsa</varname></title>

        <para>
          Allows <application>MPD</application> on Linux to play audio
          directly from a soundcard using the scheme
          <filename>alsa://</filename>. Audio is formatted as 44.1 kHz
          16-bit stereo (CD format). Examples:
        </para>

        <para>
          <filename>mpc add alsa://</filename> plays audio from device hw:0,0
        </para>
        <para>
          <filename>mpc add alsa://hw:1,0</filename> plays audio from device
          hw:1,0
        </para>
      </section>

      <section>
        <title><varname>cdio_paranoia</varname></title>

        <para>
          Plays audio CDs using <ulink
          url="http://www.gnu.org/software/libcdio/"><filename>libcdio</filename></ulink>.
          The URI has the form:
          "<filename>cdda://[DEVICE][/TRACK]</filename>".  The
          simplest form <filename>cdda://</filename> plays the whole
          disc in the default drive.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>default_byte_order</varname>
                <parameter>little_endian|big_endian</parameter>
                </entry>
                <entry>
                  If the CD drive does not specify a byte order,
                  <application>MPD</application> assumes it is the
                  CPU's native byte order.  This setting allows
                  overriding this.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>curl</varname></title>

        <para>
          Opens remote files or streams over HTTP using <ulink
          url="http://curl.haxx.se/"><filename>libcurl</filename></ulink>.
        </para>

        <para>
          Note that unless overridden by the below settings (e.g. by
          setting them to a blank value), general curl configuration
          from environment variables such as
          <varname>http_proxy</varname> or specified in
          <filename>~/.curlrc</filename> will be in effect.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>proxy</varname>
                </entry>
                <entry>
                  Sets the address of the HTTP proxy server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>proxy_user</varname>,
                  <varname>proxy_password</varname>
                </entry>
                <entry>
                  Configures proxy authentication.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>verify_peer</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Verify the peer's SSL certificate?  <ulink
                  url="http://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYPEER.html">More
                  information</ulink>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>verify_host</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Verify the certificate's name against host?  <ulink
                  url="http://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYHOST.html">More
                  information</ulink>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="ffmpeg_input">
        <title><varname>ffmpeg</varname></title>

        <para>
          Access to various network protocols implemented by the
          <application>FFmpeg</application> library:
          <filename>gopher://</filename>,
          <filename>rtp://</filename>,
          <filename>rtsp://</filename>,
          <filename>rtmp://</filename>,
          <filename>rtmpt://</filename>,
          <filename>rtmps://</filename>
        </para>
      </section>

      <section>
        <title><varname>file</varname></title>

        <para>
          Opens local files.
        </para>
      </section>

      <section>
        <title><varname>mms</varname></title>

        <para>
          Plays streams with the MMS protocol using <ulink
          url="https://launchpad.net/libmms"><filename>libmms</filename></ulink>.
        </para>
      </section>

      <section>
        <title><varname>nfs</varname></title>

        <para>
          Allows <application>MPD</application> to access files on
          NFSv3 servers without actually mounting them (i.e. in
          userspace, without help from the kernel's VFS layer).  All
          URIs with the <filename>nfs://</filename> scheme are used
          according to <ulink
          url="http://tools.ietf.org/html/rfc2224">RFC2224</ulink>.
          Example:
        </para>

        <para>
          <filename>mpc add nfs://servername/path/filename.ogg</filename>
        </para>

        <para>
          Note that this usually requires enabling the "insecure" flag
          in the server's <filename>/etc/exports</filename> file,
          because <application>MPD</application> cannot bind to
          so-called "privileged" ports.  Don't fear: this will not
          make your file server insecure; the flag was named in a time
          long ago when privileged ports were thought to be meaningful
          for security.  By today's standards, NFSv3 is not secure at
          all, and if you believe it is, you're already doomed.
        </para>
      </section>

      <section>
        <title><varname>smbclient</varname></title>

        <para>
          Allows <application>MPD</application> to access files on
          SMB/CIFS servers (e.g. Samba or Microsoft Windows).  All
          URIs with the <filename>smb://</filename> scheme are used.
          Example:
        </para>

        <para>
          <filename>mpc add smb://servername/sharename/filename.ogg</filename>
        </para>
      </section>

      <section id="qobuz_input">
        <title><varname>qobuz</varname></title>

        <para>
          Play songs from the commercial streaming service <ulink
          url="https://www.qobuz.com/">Qobuz</ulink>.  It plays URLs in the
          form <filename>qobuz://track/ID</filename>, e.g.:
        </para>

        <programlisting>mpc add qobuz://track/23601296</programlisting>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>app_id</varname>
                  <parameter>ID</parameter>
                </entry>
                <entry>
                  The Qobuz application id.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>app_secret</varname>
                  <parameter>SECRET</parameter>
                </entry>
                <entry>
                  The Qobuz application secret.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>username</varname>
                  <parameter>USERNAME</parameter>
                </entry>
                <entry>
                  The Qobuz user name.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>password</varname>
                  <parameter>PASSWORD</parameter>
                </entry>
                <entry>
                  The Qobuz password.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>format_id</varname>
                  <parameter>N</parameter>
                </entry>
                <entry>
                  The <ulink
                  url="https://github.com/Qobuz/api-documentation/blob/master/endpoints/track/getFileUrl.md#parameters">Qobuz
                  format identifier</ulink>, i.e. a number which
                  chooses the format and quality to be requested from
                  Qobuz.  The default is "5" (320 kbit/s MP3).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="tidal_input">
        <title><varname>tidal</varname></title>

        <para>
          Play songs from the commercial streaming service <ulink
          url="http://tidal.com/">Tidal</ulink>.  It plays URLs in the
          form <filename>tidal://track/ID</filename>, e.g.:
        </para>

        <programlisting>mpc add tidal://track/59727857</programlisting>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>token</varname>
                  <parameter>TOKEN</parameter>
                </entry>
                <entry>
                  The Tidal application token.  Since Tidal is
                  unwilling to assign a token to MPD, this needs to be
                  reverse-engineered from another (approved) Tidal
                  client.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>username</varname>
                  <parameter>USERNAME</parameter>
                </entry>
                <entry>
                  The Tidal user name.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>password</varname>
                  <parameter>PASSWORD</parameter>
                </entry>
                <entry>
                  The Tidal password.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>audioquality</varname>
                  <parameter>Q</parameter>
                </entry>
                <entry>
                  The Tidal "audioquality" parameter.  Possible
                  values: <parameter>HI_RES</parameter>,
                  <parameter>LOSSLESS</parameter>,
                  <parameter>HIGH</parameter>,
                  <parameter>LOW</parameter>.  Default is
                  <parameter>HIGH</parameter>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>

    <section id="decoder_plugins">
      <title>Decoder plugins</title>

      <section id="adplug_decoder">
        <title><varname>adplug</varname></title>

        <para>
          Decodes AdLib files using <ulink
          url="http://adplug.sourceforge.net/">libadplug</ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>sample_rate</varname>
                  <parameter></parameter>
                </entry>
                <entry>
                  The sample rate that shall be synthesized by the
                  plugin.  Defaults to 48000.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="audiofile_decoder">
        <title><varname>audiofile</varname></title>

        <para>
          Decodes WAV and AIFF files using <ulink
          url="http://audiofile.68k.org/"><filename>libaudiofile</filename></ulink>.
        </para>
      </section>

      <section id="faad_decoder">
        <title><varname>faad</varname></title>

        <para>
          Decodes AAC files using <ulink
          url="http://www.audiocoding.com/"><filename>libfaad</filename></ulink>.
        </para>
      </section>

      <section id="ffmpeg_decoder">
        <title><varname>ffmpeg</varname></title>

        <para>
          Decodes various codecs using <ulink
          url="https://ffmpeg.org/"><application>FFmpeg</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>analyzeduration</varname>
                  <parameter>VALUE</parameter>
                </entry>
                <entry>
                  Sets the FFmpeg muxer option
                  <varname>analyzeduration</varname>, which specifies
                  how many microseconds are analyzed to probe the
                  input.  The <ulink
                  url="https://ffmpeg.org/ffmpeg-formats.html">FFmpeg
                  formats documentation</ulink> has more information.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>probesize</varname>
                  <parameter>VALUE</parameter>
                </entry>
                <entry>
                  Sets the FFmpeg muxer option
                  <varname>probesize</varname>, which specifies
                  probing size in bytes, i.e. the size of the data to
                  analyze to get stream information.  The <ulink
                  url="https://ffmpeg.org/ffmpeg-formats.html">FFmpeg
                  formats documentation</ulink> has more information.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="flac_decoder">
        <title><varname>flac</varname></title>

        <para>
          Decodes FLAC files using
          <ulink url="https://xiph.org/flac/"><application>libFLAC</application></ulink>.
        </para>
      </section>

      <section id="dsdiff_decoder">
        <title><varname>dsdiff</varname></title>

        <para>
          Decodes DFF files containing DSDIFF data (e.g. SACD rips).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>lsbitfirst</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Decode the least significant bit first.  Default is
                  <parameter>no</parameter>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="dsf_decoder">
        <title><varname>dsf</varname></title>

        <para>
          Decodes DSF files containing DSDIFF data (e.g. SACD rips).
        </para>

      </section>

      <section>
        <title><varname>fluidsynth</varname></title>

        <para>
          MIDI decoder based on <ulink
          url="http://www.fluidsynth.org/"><application>FluidSynth</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>sample_rate</varname>
                </entry>
                <entry>
                  The sample rate that shall be synthesized by the
                  plugin.  Defaults to 48000.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>soundfont</varname>
                </entry>
                <entry>
                  The absolute path of the soundfont file.  Defaults
                  to
                  <filename>/usr/share/sounds/sf2/FluidR3_GM.sf2</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>gme</varname></title>

        <para>
          Video game music file emulator based on <ulink
          url="https://bitbucket.org/mpyne/game-music-emu/wiki/Home"><application>game-music-emu</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>accuracy</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Enable more accurate sound emulation.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="hybrid_dsd_decoder">
        <title><varname>hybrid_dsd</varname></title>

        <para>
          <ulink
              url="http://dsdmaster.blogspot.de/p/bitperfect-introduces-hybrid-dsd-file.html">Hybrid-DSD</ulink>
          is a MP4 container file (<filename>*.m4a</filename>) which
          contains both ALAC and DSD data.  It is disabled by default,
          and works only if you explicitly enable it.  Without this
          plugin, the ALAC parts gets handled by the <link
          linkend="ffmpeg_decoder">FFmpeg decoder plugin</link>.  This
          plugin should be enabled only if you have a bit-perfect
          playback path to a DSD-capable DAC; for everybody else,
          playing back the ALAC copy of the file is better.
        </para>
      </section>

      <section id="mad_decoder">
        <title><varname>mad</varname></title>

        <para>
          Decodes MP3 files using <ulink
          url="http://www.underbit.com/products/mad/"><application>libmad</application></ulink>.
        </para>
      </section>

      <section>
        <title><varname>mikmod</varname></title>

        <para>
          Module player based on <ulink
          url="http://mikmod.sourceforge.net/"><application>MikMod</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>loop</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Allow backward loops in modules.  Default is
		  <parameter>no</parameter>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>sample_rate</varname>
                </entry>
                <entry>
                  Sets the sample rate generated by
                  <filename>libmikmod</filename>.  Default is 44100.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>modplug</varname></title>

        <para>
          Module player based on <application>MODPlug</application>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>loop_count</varname>
                </entry>
                <entry>
                  Number of times to loop the module if it uses backward loops.
                  Default is <parameter>0</parameter> which prevents looping.
                  <parameter>-1</parameter> loops forever.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="mpcdec_decoder">
        <title><varname>mpcdec</varname></title>

        <para>
          Decodes Musepack files using <ulink
          url="http://www.musepack.net/"><application>libmpcdec</application></ulink>.
        </para>
      </section>

      <section id="mpg123_decoder">
        <title><varname>mpg123</varname></title>

        <para>
          Decodes MP3 files using <ulink
          url="http://www.mpg123.de/"><application>libmpg123</application></ulink>.
        </para>
      </section>

      <section id="opus_decoder">
        <title><varname>opus</varname></title>

        <para>
          Decodes Opus files using <ulink
          url="http://www.opus-codec.org/"><application>libopus</application></ulink>.
        </para>
      </section>

      <section>
        <title><varname>pcm</varname></title>

        <para>
          Read raw PCM samples.  It understands the "audio/L16" MIME
          type with parameters "rate" and "channels" according to RFC
          2586.  It also understands the
          <application>MPD</application>-specific MIME type
          "audio/x-mpd-float".
        </para>
      </section>

      <section id="sidplay_decoder">
        <title><varname>sidplay</varname></title>

        <para>
          C64 SID decoder based on <ulink
          url="http://sidplay2.sourceforge.net/"><application>libsidplay</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>songlength_database</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Location of your songlengths file, as distributed
                  with the HVSC.  The <varname>sidplay</varname>
                  plugin checks this for matching MD5 fingerprints.
                  See <ulink url="http://www.hvsc.c64.org/download/C64Music/DOCUMENTS/Songlengths.faq"/>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>default_songlength</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  This is the default playing time in seconds for
                  songs not in the songlength database, or in case
                  you're not using a database.  A value of 0 means
                  play indefinitely.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>filter</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Turns the SID filter emulation on or off.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="sndfile_decoder">
        <title><varname>sndfile</varname></title>

        <para>
          Decodes WAV and AIFF files using <ulink
          url="http://www.mega-nerd.com/libsndfile/"><filename>libsndfile</filename></ulink>.
        </para>
      </section>

      <section id="vorbis_decoder">
        <title><varname>vorbis</varname></title>

        <para>
          Decodes Ogg-Vorbis files using <ulink
          url="http://www.xiph.org/ogg/vorbis/"><application>libvorbis</application></ulink>.
        </para>
      </section>

      <section id="wavpack_decoder">
        <title><varname>wavpack</varname></title>

        <para>
          Decodes WavPack files using
          <ulink url="http://www.wavpack.com/"><application>libwavpack</application></ulink>.
        </para>
      </section>

      <section>
        <title><varname>wildmidi</varname></title>

        <para>
          MIDI decoder based on <ulink
          url="http://www.mindwerks.net/projects/wildmidi/"><application>libwildmidi</application></ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>config_file</varname>
                </entry>
                <entry>
                  The absolute path of the timidity config file.  Defaults
                  to
                  <filename>/etc/timidity/timidity.cfg</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>

    <section id="encoder_plugins">
      <title>Encoder plugins</title>

      <section>
        <title><varname>flac</varname></title>

        <para>
          Encodes into <ulink
          url="https://xiph.org/flac/">FLAC</ulink> (lossless).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>compression</varname>
                </entry>
                <entry>
                  Sets the <filename>libFLAC</filename> compression
                  level.  The levels range from 0 (fastest, least
                  compression) to 8 (slowest, most compression).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>lame</varname></title>

        <para>
          Encodes into MP3 using the <ulink
          url="http://lame.sourceforge.net/"><application>LAME</application></ulink>
          library.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  Sets the quality for VBR.  0 is the highest quality,
                  9 is the lowest quality.  Cannot be used with
                  <varname>bitrate</varname>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.  Cannot be
                  used with <varname>quality</varname>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>null</varname></title>

        <para>
          Does not encode anything, passes the input PCM data as-is.
        </para>
      </section>

      <section>
        <title><varname>shine</varname></title>

        <para>
          Encodes into MP3 using the <ulink
          url="https://github.com/savonet/shine"><application>Shine</application></ulink>
          library.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>twolame</varname></title>

        <para>
          Encodes into MP2 using the <ulink
          url="http://www.twolame.org/"><application>TwoLAME</application></ulink>
          library.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  Sets the quality for VBR.  0 is the highest quality,
                  9 is the lowest quality.  Cannot be used with
                  <varname>bitrate</varname>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.  Cannot be
                  used with <varname>quality</varname>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="opus_encoder">
        <title><varname>opus</varname></title>

        <para>
          Encodes into <ulink
          url="http://www.opus-codec.org/">Ogg Opus</ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the data rate in bit per second.  The special
                  value "auto" lets <application>libopus</application>
                  choose a rate (which is the default), and "max" uses
                  the maximum possible data rate.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>complexity</varname>
                </entry>
                <entry>
                  Sets the <ulink
                  url="https://wiki.xiph.org/OpusFAQ#What_is_the_complexity_of_Opus.3F">Opus
                  complexity</ulink>.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>signal</varname>
                </entry>
                <entry>
                  Sets the Opus signal type.  Valid values are "auto"
                  (the default), "voice" and "music".
                </entry>
              </row>

              <row>
                <entry>
                  <varname>opustags</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Configures how metadata is interleaved into the stream.
                  If set to <parameter>yes</parameter>, then metadata
                  is inserted using ogg stream chaining, as specified
                  in <ulink url="https://tools.ietf.org/html/rfc7845.html#section-7.2">RFC
                  7845</ulink>. If set to <parameter>no</parameter>
                  (the default), then ogg stream chaining is avoided
                  and other output-dependent method is used, if
                  available.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="vorbis_encoder">
        <title><varname>vorbis</varname></title>

        <para>
          Encodes into <ulink url="http://www.vorbis.com/">Ogg
          Vorbis</ulink>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  Sets the quality for VBR.  -1 is the lowest quality,
                  10 is the highest quality.  Defaults to 3.  Cannot
                  be used with <varname>bitrate</varname>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bitrate</varname>
                </entry>
                <entry>
                  Sets the bit rate in kilobit per second.  Cannot be
                  used with <varname>quality</varname>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>wave</varname></title>

        <para>
          Encodes into WAV (lossless).
        </para>
      </section>
    </section>

    <section id="resampler_plugins">
      <title>Resampler plugins</title>

      <para>
        The resampler can be configured in a block named
        <varname>resampler</varname>, for example:
      </para>

      <programlisting>resampler {
  plugin "soxr"
  quality "very high"
}</programlisting>

      <para>
        The following table lists the <varname>resampler</varname>
        options valid for all plugins:
      </para>

      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>
                Name
              </entry>
              <entry>
                Description
              </entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>
                <varname>plugin</varname>
              </entry>
              <entry>
                The name of the plugin.
              </entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>

      <section id="internal_resampler">
        <title><varname>internal</varname></title>

        <para>
          A resampler built into <application>MPD</application>.  Its
          quality is very poor, but its CPU usage is low.  This is the
          fallback if <application>MPD</application> was compiled
          without an external resampler.
        </para>
      </section>

      <section id="libsamplerate_resampler">
        <title><varname>libsamplerate</varname></title>

        <para>
          A resampler using <ulink
          url="http://www.mega-nerd.com/SRC/"><application>libsamplerate</application></ulink>
          a.k.a. Secret Rabbit Code (SRC).
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>
                  Name
                </entry>
                <entry>
                  Description
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>type</varname>
                </entry>
                <entry>
                  The interpolator type.  See below for a list of
                  known types.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>

        <para>
          The following converter types are provided by
          <application>libsamplerate</application>:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>
                  Type
                </entry>
                <entry>
                  Description
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  "<parameter>Best Sinc Interpolator</parameter>" or
                  "<parameter>0</parameter>"
                </entry>
                <entry>
                  Band limited sinc interpolation, best quality, 97dB
                  SNR, 96% BW.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>Medium Sinc Interpolator</parameter>" or
                  "<parameter>1</parameter>"
                </entry>
                <entry>
                  Band limited sinc interpolation, medium quality,
                  97dB SNR, 90% BW.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>Fastest Sinc Interpolator</parameter>" or
                  "<parameter>2</parameter>"
                </entry>
                <entry>
                  Band limited sinc interpolation, fastest, 97dB SNR,
                  80% BW.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>ZOH Sinc Interpolator</parameter>" or
                  "<parameter>3</parameter>"
                </entry>
                <entry>
                  Zero order hold interpolator, very fast, very poor
                  quality with audible distortions.
                </entry>
              </row>

              <row>
                <entry>
                  "<parameter>Linear Interpolator</parameter>" or
                  "<parameter>4</parameter>"
                </entry>
                <entry>
                  Linear interpolator, very fast, poor quality.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="soxr_resampler">
        <title><varname>soxr</varname></title>

        <para>
          A resampler using <ulink
          url="http://sourceforge.net/projects/soxr/"><application>libsoxr</application></ulink>,
          the SoX Resampler library
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>
                  Name
                </entry>
                <entry>
                  Description
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>quality</varname>
                </entry>
                <entry>
                  The <application>libsoxr</application> quality
                  setting.  Valid values are:

                  <itemizedlist>
                    <listitem>
                      <para>
                        "<parameter>very high</parameter>"
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>high</parameter>" (the default)
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>medium</parameter>"
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>low</parameter>"
                      </para>
                    </listitem>

                    <listitem>
                      <para>
                        "<parameter>quick</parameter>"
                      </para>
                    </listitem>
                  </itemizedlist>
                </entry>
              </row>

              <row>
                <entry>
                  <varname>threads</varname>
                </entry>
                <entry>
                  The number of <application>libsoxr</application>
                  threads.  "0" means "automatic".  The default is "1"
                  which disables multi-threading.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>

    <section id="output_plugins">
      <title>Output plugins</title>

      <section id="alsa_output">
        <title><varname>alsa</varname></title>

        <para>
          The <ulink
          url="http://www.alsa-project.org/"><application>Advanced
          Linux Sound Architecture</application>
          (<application>ALSA</application>)</ulink> plugin uses
          <filename>libasound</filename>.  It is recommended if you
          are using Linux.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Sets the device which should be used.  This can be
                  any valid ALSA device name.  The default value is
                  "default", which makes
                  <filename>libasound</filename> choose a device.  It
                  is recommended to use a "hw" or "plughw" device,
                  because otherwise, <filename>libasound</filename>
                  automatically enables "dmix", which has major
                  disadvantages (fixed sample rate, poor resampler,
                  ...).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>buffer_time</varname>
                  <parameter>US</parameter>
                </entry>
                <entry>
                  Sets the device's buffer time in microseconds.
                  Don't change unless you know what you're doing.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>period_time</varname>
                  <parameter>US</parameter>
                </entry>
                <entry>
                  Sets the device's period time in microseconds.
                  Don't change unless you really know what you're
                  doing.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>auto_resample</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then
                  <filename>libasound</filename> will not attempt to
                  resample, handing the responsibility over to
                  <application>MPD</application>.  It is recommended
                  to let <application>MPD</application> resample (with
                  <application>libsamplerate</application>), because
                  ALSA is quite poor at doing so.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>auto_channels</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then
                  <filename>libasound</filename> will not attempt to
                  convert between different channel numbers.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>auto_format</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then
                  <filename>libasound</filename> will not attempt to
                  convert between different sample formats (16 bit, 24
                  bit, floating point, ...).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>dop</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>yes</parameter>, then DSD over
                  PCM according to the <ulink
                  url="http://dsd-guide.com/dop-open-standard">DoP
                  standard</ulink> is enabled.  This wraps DSD
                  samples in fake 24 bit PCM, and is understood by
                  some DSD capable products, but may be harmful to
                  other hardware.  Therefore, the default is
                  <parameter>no</parameter> and you can enable the
                  option at your own risk.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>allowed_formats</varname>
                  <parameter>F1 F2 ...</parameter>
                </entry>
                <entry>
                  <para>
                    Specifies a list of allowed audio formats, separated
                    by a space.  All items may contain asterisks as a
                    wild card, and may be followed by
                    "<parameter>=dop</parameter>" to enable DoP (DSD
                    over PCM) for this particular format.  The first
                    matching format is used, and if none matches, MPD
                    chooses the best fallback of this list.
                  </para>
                  <para>
                    Example: "<parameter>96000:16:* 192000:24:*
                    dsd64:*=dop *:dsd:*</parameter>".
                  </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>

        <para>
          The according hardware mixer plugin understands the
          following settings:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>mixer_device</varname>
                  <parameter>DEVICE</parameter>
                </entry>
                <entry>
                  <para>
                    Sets the ALSA mixer device name, defaulting to
                    <parameter>default</parameter> which lets ALSA
                    pick a value.
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <varname>mixer_control</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  <para>
                    Choose a mixer control, defaulting to
                    <parameter>PCM</parameter>.  Type <command>amixer
                    scontrols</command> to get a list of available
                    mixer controls.
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <varname>mixer_index</varname>
                  <parameter>NUMBER</parameter>
                </entry>
                <entry>
                  Choose a mixer control index.  This is necessary if
                  there is more than one control with the same name.
                  Defaults to <parameter>0</parameter> (the first
                  one).
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>

        <para>
          The following attributes can be configured at runtime using
          the <command>outputset</command> command:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>dop</varname>
                  <parameter>1|0</parameter>
                </entry>
                <entry>
                  <para>
                    Allows changing the <varname>dop</varname>
                    configuration setting at runtime.  This takes
                    effect the next time the output is opened.
                  </para>
                </entry>
              </row>

              <row>
                <entry>
                  <varname>allowed_formats</varname>
                  <parameter>F1 F2 ...</parameter>
                </entry>
                <entry>
                  <para>
                    Allows changing the
                    <varname>allowed_formats</varname> configuration
                    setting at runtime.  This takes effect the next
                    time the output is opened.
                  </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>ao</varname></title>

        <para>
          The <varname>ao</varname> plugin uses the portable <ulink
          url="https://www.xiph.org/ao/"><filename>libao</filename></ulink>
          library.  Use only if there is no native plugin for your
          operating system.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>driver</varname>
                  <parameter>D</parameter>
                </entry>
                <entry>
                  The <filename>libao</filename> driver to use for
                  audio output.  Possible values depend on what libao
                  drivers are available.  See <ulink
                  url="http://www.xiph.org/ao/doc/drivers.html">http://www.xiph.org/ao/doc/drivers.html</ulink>
                  for information on some commonly used drivers.
                  Typical values for Linux include "oss" and "alsa09".
                  The default is "default", which causes libao to
                  select an appropriate plugin.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>options</varname>
                  <parameter>O</parameter>
                </entry>
                <entry>
                  Options to pass to the selected
                  <filename>libao</filename> driver.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>write_size</varname>
                  <parameter>O</parameter>
                </entry>
                <entry>
                  This specifies how many bytes to write to the audio
                  device at once.  This parameter is to work around a
                  bug in older versions of libao on sound cards with
                  very small buffers.  The default is 1024.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>sndio</varname></title>

        <para>
          The <varname>sndio</varname> plugin uses the <ulink
          url="http://www.sndio.org/">sndio</ulink> library.  It should normally be used
          on OpenBSD.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  The audio output device <filename>libsndio</filename>
                  will attempt to use.  The default is "default" which
                  causes libsndio to select the first output device.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>buffer_time</varname>
                  <parameter>MS</parameter>
                </entry>
                <entry>
                  Set the application buffer time in milliseconds.
                </entry>
              </row>

            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>fifo</varname></title>

        <para>
          The <varname>fifo</varname> plugin writes raw PCM data to a
          FIFO (First In, First Out) file.  The data can be read by
          another program.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>path</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  This specifies the path of the FIFO to write to.
                  Must be an absolute path.  If the path does not
                  exist, it will be created when
                  <application>MPD</application> is started, and
                  removed when <application>MPD</application> is
                  stopped.  The FIFO will be created with the same
                  user and group as <application>MPD</application> is
                  running as.  Default permissions can be modified by
                  using the builtin shell command
                  <filename>umask</filename>.  If a FIFO already
                  exists at the specified path it will be reused, and
                  will not be removed when
                  <application>MPD</application> is stopped.  You can
                  use the "mkfifo" command to create this, and then
                  you may modify the permissions to your liking.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="jack_output">
        <title><varname>jack</varname></title>

        <para>
          The <varname>jack</varname> plugin connects to a <ulink
          url="http://jackaudio.org/"><application>JACK</application></ulink>
          server.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>client_name</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  The name of the <application>JACK</application>
                  client.  Defaults to "Music Player Daemon".
                </entry>
              </row>
              <row>
                <entry>
                  <varname>server_name</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Optional name of the <application>JACK</application>
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>autostart</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>yes</parameter>, then
                  <filename>libjack</filename> will automatically
                  launch the <application>JACK</application> daemon.
                  Disabled by default.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>source_ports</varname>
                  <parameter>A,B</parameter>
                </entry>
                <entry>
                  The names of the <application>JACK</application>
                  source ports to be created.  By default, the ports
                  "left" and "right" are created.  To use more ports,
                  you have to tweak this option.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>destination_ports</varname>
                  <parameter>A,B</parameter>
                </entry>
                <entry>
                  The names of the <application>JACK</application>
                  destination ports to connect to.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>ringbuffer_size</varname>
                  <parameter>NBYTES</parameter>
                </entry>
                <entry>
                  Sets the size of the ring buffer for each channel.
                  Do not configure this value unless you know what
                  you're doing.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="httpd_output">
        <title><varname>httpd</varname></title>

        <para>
          The <varname>httpd</varname> plugin creates a HTTP server,
          similar to <ulink
          url="http://www.shoutcast.com/"><application>ShoutCast</application></ulink>
          / <ulink
          url="http://icecast.org/"><application>IceCast</application></ulink>.
          HTTP streaming clients like
          <application>mplayer</application>, <application>VLC</application>,
          and <application>mpv</application> can connect to it.
        </para>

        <para>
          It is highly recommended to configure a fixed
          <varname>format</varname>, because a stream cannot switch
          its audio format on-the-fly when the song changes.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>port</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  Binds the HTTP server to the specified port.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>bind_to_address</varname>
                  <parameter>ADDR</parameter>
                </entry>
                <entry>
                  Binds the HTTP server to the specified address (IPv4 or
                  IPv6). Multiple addresses in parallel are not supported.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>encoder</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Chooses an encoder plugin.  A list of encoder
                  plugins can be found in the <link
                  linkend="encoder_plugins">encoder plugin
                  reference</link>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>max_clients</varname>
                  <parameter>MC</parameter>
                </entry>
                <entry>
                  Sets a limit, number of concurrent clients. When set
                  to 0 no limit will apply.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>null</varname></title>

        <para>
          The <varname>null</varname> plugin does nothing.  It
          discards everything sent to it.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>sync</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>no</parameter>, then the timer
                  is disabled - the device will accept PCM chunks at
                  arbitrary rate (useful for benchmarking).  The
                  default behaviour is to play in real time.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="oss_output">
        <title><varname>oss</varname></title>

        <para>
          The "Open Sound System" plugin is supported on most Unix
          platforms.
        </para>

        <para>
          On Linux, <application>OSS</application> has been superseded
          by <application>ALSA</application>.  Use the <link
          linkend="alsa_output"><application>ALSA</application> output
          plugin</link> instead of this one on Linux.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Sets the path of the PCM device.  If not specified,
                  then <application>MPD</application> will attempt to
                  open <filename>/dev/sound/dsp</filename> and
                  <filename>/dev/dsp</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>

        <para>
          The according hardware mixer plugin understands the
          following settings:
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>mixer_device</varname>
                  <parameter>DEVICE</parameter>
                </entry>
                <entry>
                  <para>
                    Sets the OSS mixer device path, defaulting to
                    <filename>/dev/mixer</filename>.
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <varname>mixer_control</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  <para>
                    Choose a mixer control, defaulting to
                    <parameter>PCM</parameter>.
                  </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="openal_output">
        <title><varname>openal</varname></title>

        <para>
          The "OpenAL" plugin uses <ulink
          url="http://kcat.strangesoft.net/openal.html"><filename>libopenal</filename></ulink>.
          It is supported on many platforms.  Use only if there is no
          native plugin for your operating system.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Sets the device which should be used.  This can be
                  any valid OpenAL device name. If not specified, then
                  <filename>libopenal</filename> will choose a default device.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>osx</varname></title>

        <para>
          The "Mac OS X" plugin uses Apple's CoreAudio API.
        </para>
        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Sets the device which should be used. Uses device names as listed in the
                  "Audio Devices" window of "Audio MIDI Setup".
                </entry>
              </row>
              <row>
                <entry>
                  <varname>hog_device</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Hog the device. This means that it takes exclusive control of the audio
                  output device it is playing through, and no other program can access it.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>sync_sample_rate</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Synchronize the sample rate. It will try to set the output device sample
                  rate to the corresponding sample rate of the file playing. If the output
                  device does not support the sample rate the track has, it will try to 
                  select the best possible for each file.
                </entry>
              </row>
	      <row>
                <entry>
                  <varname>dop</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  If set to <parameter>yes</parameter>, then DSD over
                  PCM according to the <ulink
                    url="http://dsd-guide.com/dop-open-standard">DoP
                    standard</ulink> is enabled.  This wraps DSD
                  samples in fake 24 bit PCM, and is understood by
                  some DSD capable products, but may be harmful to
                  other hardware.  Therefore, the default is
                  <parameter>no</parameter> and you can enable the
                  option at your own risk. Under macOS you must
                  make sure to select a physical mode on the output
                  device which supports at least 24 bits per channel
                  as the Mac OS X plugin only changes the sample rate.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>channel_map</varname>
                  <parameter>SOURCE,SOURCE,...</parameter>
                </entry>
                <entry><para>
                    Specifies a channel map. If your audio device has more than two
                    outputs this allows you to route audio to auxillary outputs. For
                    predictable results you should also specify a "format" with a fixed
                    number of channels, e.g. "*:*:2". The number of items in the channel
                    map must match the number of output channels of your output device.
                    Each list entry specifies the source for that output channel; use "-1"
                    to silence an output. For example, if you have a four-channel output
                    device and you wish to send stereo sound (format "*:*:2") to outputs 3
                    and 4 while leaving outputs 1 and 2 silent then set the channel map to
                    "-1,-1,0,1". In this example '0' and '1' denote the left and right
                    channel respectively.
                  </para>
                  <para>
                    The channel map may not refer to outputs that do not exist according
                    to the format. If the format is "*:*:1" (mono) and you have a
                    four-channel sound card then "-1,-1,0,0" (dual mono output on the
                    second pair of sound card outputs) is a valid channel map but
                    "-1,-1,0,1" is not because the second channel ('1') does not exist
                    when the output is mono.
                </para></entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>pipe</varname></title>

        <para>
          The <varname>pipe</varname> plugin starts a program and
          writes raw PCM data into its standard input.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>command</varname>
                  <parameter>CMD</parameter>
                </entry>
                <entry>
                  This command is invoked with the shell.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="pulse_output">
        <title><varname>pulse</varname></title>

        <para>
          The <varname>pulse</varname> plugin connects to a <ulink
          url="http://www.freedesktop.org/wiki/Software/PulseAudio/"><application>PulseAudio</application></ulink>
          server.  Requires <filename>libpulse</filename>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>server</varname>
                  <parameter>HOSTNAME</parameter>
                </entry>
                <entry>
                  Sets the host name of the
                  <application>PulseAudio</application> server.  By
                  default, <application>MPD</application> connects to
                  the local <application>PulseAudio</application>
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>sink</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Specifies the name of the
                  <application>PulseAudio</application> sink
                  <application>MPD</application> should play on.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>roar</varname></title>

        <para>
          The <varname>roar</varname> plugin connects to a <ulink
          url="http://roaraudio.keep-cool.org/">RoarAudio</ulink>
          server.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>server</varname>
                  <parameter>HOSTNAME</parameter>
                </entry>
                <entry>
                  The host name of the RoarAudio server.  If not
                  specified, then <application>MPD</application> will
                  connect to the default locations.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>role</varname>
                  <parameter>ROLE</parameter>
                </entry>
                <entry>
                  The "role" that <application>MPD</application>
                  registers itself as in the RoarAudio server.  The
                  default is "music".
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>recorder</varname></title>

        <para>
          The <varname>recorder</varname> plugin writes the audio
          played by <application>MPD</application> to a file.  This
          may be useful for recording radio streams.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>path</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  Write to this file.
                </entry>
              </row>

              <row>
                <entry>
                  <varname>format_path</varname>
                  <parameter>P</parameter>
                </entry>
                <entry>
                  <para>
                    An alternative to <varname>path</varname> which
                    provides a format string referring to tag values.

                    The special tag <varname>iso8601</varname> emits
                    the current date and time in <ulink
                    url="https://en.wikipedia.org/wiki/ISO_8601">ISO8601</ulink>
                    format (UTC).
                    Every time a new song starts or a new tag gets
                    received from a radio station, a new file is
                    opened.  If the format does not render a file
                    name, nothing is recorded.
                  </para>

                  <para>
                    A tag name enclosed in percent signs ('%') is
                    replaced with the tag value.  Example:
                    <parameter>~/.mpd/recorder/%artist% -
                    %title%.ogg</parameter>
                  </para>

                  <para>
                    Square brackets can be used to group a substring.
                    If none of the tags referred in the group can be
                    found, the whole group is omitted.  Example:
                    <parameter>[~/.mpd/recorder/[%artist% -
                    ]%title%.ogg]</parameter> (this omits the dash
                    when no artist tag exists; if title also doesn't
                    exist, no file is written)
                  </para>

                  <para>
                    The operators "|" (logical "or") and "&amp;"
                    (logical "and") can be used to select portions of
                    the format string depending on the existing tag
                    values.  Example:
                    <parameter>~/.mpd/recorder/[%title%|%name%].ogg</parameter>
                    (use the "name" tag if no title exists)
                  </para>
                </entry>
              </row>

              <row>
                <entry>
                  <varname>encoder</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Chooses an encoder plugin.  A list of encoder
                  plugins can be found in the <link
                  linkend="encoder_plugins">encoder plugin
                  reference</link>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section id="shout_output">
        <title><varname>shout</varname></title>

        <para>
          The <varname>shout</varname> plugin connects to a <ulink
          url="http://www.shoutcast.com/"><application>ShoutCast</application></ulink>
          or <ulink
          url="http://icecast.org/"><application>IceCast</application></ulink>
          server using <filename>libshout</filename>.  It forwards
          tags to this server.
        </para>

        <para>
          You must set a <varname>format</varname>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>host</varname>
                  <parameter>HOSTNAME</parameter>
                </entry>
                <entry>
                  Sets the host name of the <ulink
                  url="http://www.shoutcast.com/"><application>ShoutCast</application></ulink>
                  / <ulink
                  url="http://icecast.org/"><application>IceCast</application></ulink>
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>port</varname>
                  <parameter>PORTNUMBER</parameter>
                </entry>
                <entry>
                  Connect to this port number on the specified host.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>timeout</varname>
                  <parameter>SECONDS</parameter>
                </entry>
                <entry>
                  Set the timeout for the shout connection in seconds.
                  Defaults to 2 seconds.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>protocol</varname>
                  <parameter>icecast2|icecast1|shoutcast</parameter>
                </entry>
                <entry>
                  Specifies the protocol that wil be used to connect
                  to the server.  The default is
                  "<parameter>icecast2</parameter>".

                </entry>
              </row>
              <row>
                <entry>
                  <varname>mount</varname>
                  <parameter>URI</parameter>
                </entry>
                <entry>
                  Mounts the <application>MPD</application> stream in
                  the specified URI.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>user</varname>
                  <parameter>USERNAME</parameter>
                </entry>
                <entry>
                  Sets the user name for submitting the stream to the
                  server.  Default is "source".
                </entry>
              </row>
              <row>
                <entry>
                  <varname>password</varname>
                  <parameter>PWD</parameter>
                </entry>
                <entry>
                  Sets the password for submitting the stream to the
                  server.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>name</varname>
                  <parameter>NAME</parameter>
                </entry>
                <entry>
                  Sets the name of the stream.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>genre</varname>
                  <parameter>GENRE</parameter>
                </entry>
                <entry>
                  Sets the genre of the stream (optional).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>description</varname>
                  <parameter>DESCRIPTION</parameter>
                </entry>
                <entry>
                  Sets a short description of the stream (optional).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>url</varname>
                  <parameter>URL</parameter>
                </entry>
                <entry>
                  Sets a URL associated with the stream (optional).
                </entry>
              </row>
              <row>
                <entry>
                  <varname>public</varname>
                  <parameter>yes|no</parameter>
                </entry>
                <entry>
                  Specifies whether the stream should be "public".
                  Default is <parameter>no</parameter>.
                </entry>
              </row>
              <row>
                <entry>
                  <varname>encoder</varname>
                  <parameter>PLUGIN</parameter>
                </entry>
                <entry>
                  Chooses an encoder plugin.  Default is <link
                  linkend="vorbis_encoder"><parameter>vorbis</parameter></link>.
                  A list of encoder plugins can be found in the <link
                  linkend="encoder_plugins">encoder plugin
                  reference</link>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>solaris</varname></title>

        <para>
          The "Solaris" plugin runs only on SUN Solaris, and plays via
          <filename>/dev/audio</filename>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>device</varname>
                  <parameter>PATH</parameter>
                </entry>
                <entry>
                  Sets the path of the audio device, defaults to
                  <filename>/dev/audio</filename>.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>
    </section>

    <section id="playlist_plugins">
      <title>Playlist plugins</title>

      <section>
        <title><varname>asx</varname></title>

        <para>
          Reads <filename>.asx</filename> playlist files.
        </para>
      </section>

      <section>
        <title><varname>cue</varname></title>

        <para>
          Reads <filename>.cue</filename> files.
        </para>
      </section>

      <section>
        <title><varname>embcue</varname></title>

        <para>
          Reads CUE sheets from the "CUESHEET" tag of song files.
        </para>
      </section>

      <section>
        <title><varname>m3u</varname></title>

        <para>
          Reads <filename>.m3u</filename> playlist files.
        </para>
      </section>

      <section>
        <title><varname>extm3u</varname></title>

        <para>
          Reads extended <filename>.m3u</filename> playlist files.
        </para>
      </section>

      <section>
        <title><varname>flac</varname></title>

        <para>
          Reads the <varname>cuesheet</varname> metablock from a FLAC
          file.
        </para>
      </section>

      <section>
        <title><varname>pls</varname></title>

        <para>
          Reads <filename>.pls</filename> playlist files.
        </para>
      </section>

      <section>
        <title><varname>rss</varname></title>

        <para>
          Reads music links from <filename>.rss</filename> files.
        </para>
      </section>

      <section>
        <title><varname>soundcloud</varname></title>

        <para>
          Download playlist from SoundCloud.  It accepts URIs starting
          with <filename>soundcloud://</filename>.
        </para>

        <informaltable>
          <tgroup cols="2">
            <thead>
              <row>
                <entry>Setting</entry>
                <entry>Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <varname>apikey</varname>
                  <parameter>KEY</parameter>
                </entry>
                <entry>
                  An API key to access the SoundCloud servers.
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </section>

      <section>
        <title><varname>xspf</varname></title>

        <para>
          Reads <ulink url="http://www.xspf.org/">XSPF</ulink>
          playlist files.
        </para>
      </section>
    </section>
  </chapter>
</book>